Abstract: A system and method is provided for facilitating navigation techniques in a three-dimensional virtual environment. The present invention couples input driving techniques to the state of one or more workspace variables (e.g., object state, virtual body state, environment state) to change the user's viewing context within a single input control motion. Modification of the user's viewing context allows navigation to various positions and orientations with out the need to be provided with that viewing context prior to navigation. The modification of the user's viewing context also allows for single input motion employing the same input drive controls.

Abstract: An input device that transmits, to a host device having a display displaying a pointer, information relating to the pointer and includes a sensor detecting contact information, and further includes an area extracting part and a control part. The area extracting part extracts a contact area of the sensor and a finger based on the contact information detected by the sensor. The control part controls the pointer based on the contact area extracted by the area extracting part.

Abstract: An input unit has a mouse function and at least one inputting function. The input unit comprises image-recording means (8) which record images. These images are used for providing both the mouse function and the inputting function. The images are processed in the input unit or in some other unit.

Abstract: A method and system for determining the position of a movable member in an electronic input device within a predefined resolution. Two offset signals indicate the position of the movable member. The time required for each signal to cross a threshold level is measured and inverted, revealing an offset sinusoidal relationship. The offset sinusoids may be plotted against each other to reveal an approximate circle of inverse time samples for a cycle. Corresponding inverted minimum and maximum times are used to determine a center reference value for each signal. As a function of the inverted times, a quadrant of the circle is determined. Within a quadrant, a sector most closely corresponding to the position of the movable member is determined from among a plurality of predefined sectors that define the resolution. A number of sectors between position samples of the movable member are accumulated and communicated to a host device.

Abstract: A multifunctional photoelectric switch comprises a display section for displaying a first display information and a second display information. The first display information includes a plurality of items concerning a threshold value and the second display information includes a plurality of items concerning functions of the photoelectric switch. A switch is provided for switching information to be displayed on the display section between each type of display information. A selection menu for the user to select either “Easy” or “Pro” is displayed in the progress of making a transition from a “light reception amount and/or threshold value display” mode of the basic display information to an “operation function setting” mode of the second display information. The user selects and sets either “Easy” or “Pro” on the selection screen. In the “Pro” mode, the set items concerning all functions are displayed; in the “Easy” mode, only the basic items are displayed.

Abstract: An input device with a pressure-sensitive element using a pressure sensing resistor. A solid elastomeric material is mounted over the pressure sensing resistor to transfer a force from the user's finger to the pressure sensitive resistor without visible deformation of the elastomeric material. This provides a comfortable button for a user which does not require the compression of a domed cap to provide pressure-sensing input. In another aspect of the invention, a pressure-sensing input element utilizes both the amount of pressure and the amount of time to determine the type of signal provided to the electronic system. In another aspect of the present invention, an input device contains a first scrolling element (e.g. a wheel) and includes a switch button mounted close to the scrolling element to activate continuous scrolling.

Abstract: A cursor positioning device that can be sealed if the environment requires sealing, that can withstand harsh use, and can position the cursor easily and quickly. In operation the where the operator places their fingers on the positioning articulator and rocks or slides the articulator in the direction they want the cursor to move. And with movement signatures do single and double clicks, and character strings to the host computer, either through the mouse port or the keyboard port. The key and articulator interrupters block optical beams for key and mouse like positioning thus eliminating any physical contact or force from articulator to detecting optics. Cursor position is positioned by an interrupter disposed in a ring of optical emitters and detectors, whereas depending on the position of movement by the positioning interrupter emission is blocked, or partially blocked, between a particular pair or pairs of emitters and detectors, that particular pair or pairs being the direction of cursor movement.

Abstract: A system, method, and method of manufacturing directed to an optical device with increased accuracy in tracking ability. The increased accuracy can be achieved by using a multiple sensor system. A second sensor is added to the optical device. The second sensor increases the probability of obtaining a high quality image. Thus, the tracking ability of the device can be performed with greater accuracy over a single sensor device. The second sensor can also perform additional functions.

Abstract: In detecting units for detecting the rotating operation of a ball, respective photoemitters serving as light sources are intermittently driven to emit light and respective photodetectors receive the light. A control unit recognizes a moving speed in the X-axial direction and that in the Y-axial direction from detection signals obtained by the detecting units. In the control operation of the control unit, when an increase in operating speed is detected, a light emitting period of each of the photoemitters is reduced. When a decrease in operating speed is detected, the light emitting period of each photoemitter is extended.

Abstract: A computer pointing device, such as a mouse or trackball, includes a reverse cantilever button assembly to match strength-related variations in user hand size. In one embodiment a button assembly is built with two cantilever beams, the fulcrums for each beam being at opposite ends of the button assembly. The stiffness of the two beams can be selected to obtain an increasing, decreasing, or constant force profile necessary to activate the associated electronic switch as one moves along the external surface of the button assembly from the palm end toward the fingertip end. An increasing force profile provides lower actuating force for operators with smaller hands, while providing greater tactile feedback for operators with larger hands.

Abstract: According to one aspect of the invention an apparatus is provided for remotely controlling a digital processing system, comprising a housing, a scrolling detector, a cursor positioning detector, and a transmitter. The housing has a wall having an outer scrolling surface over which a finger of a person's hand is movable in a scrolling movement. The scrolling detector is located within the housing. The scrolling detector detects the scrolling movement remotely through the wall and generates a scrolling signal. The cursor positioning detector is secured to the housing and is actuable by the hand to generate a position signal. The transmitter transmits the scrolling signal and the position signal to the digital processing system.

Abstract: According to one aspect of the invention, a movable cursor control device is provided for controlling a cursor on a display screen of a digital processing system. One exemplary cursor control device comprises a housing, an electromagnetic emitting device coupled to the housing, and an electromagnetic detector coupled to the housing. The electromagnetic detector detects reflections of signals emitted from the electromagnetic emitting device and determines when the housing has been lifted from a surface. In another aspect of the invention, an exemplary method is provided for controlling a cursor on a display screen of a digital processing system. The exemplary method includes holding the cursor relative to an object on the display screen using a cursor control device activated by a user, detecting that the user no longer activates the cursor control device, and detecting that the user has lifted the cursor control device from a surface when the cursor control device is no longer activated by the user.

Abstract: An apparatus and method are described herein, which simultaneously promotes a positive computing experience for users of portable computer systems and increases overall durability and longevity thereof. In one embodiment, an optical apparatus enhances the user computing experience, in one embodiment by simplifying operation, and is much more durable and long-lasting than mechanical switch and dial type devices it may replace. In one embodiment, the present invention is directed to an apparatus, which enables efficient portable computer device function, field, and data selection, gaming, input, interconnection, and other switching-related functions, simplifying operation and enhancing versatility thereof, yet without exposing the portable computer interior to any degree to incursion of environmental contamination. In one embodiment, an optical apparatus obviates openings in a portable computer package which would otherwise be required.

Abstract: An apparatus for controlling the position of a screen pointer for an electronic device having a display screen includes a pushbutton for selecting an item displayed on the display screen. The pushbutton includes an imaging surface against which a portion of the tip of a human digit may be placed. A light source illuminates that portion of the tip of the digit that is placed against the imaging surface, thereby generating reflected images. The apparatus includes a motion transducer. A lens receives the reflected images and directs the reflected images onto the motion transducer. The motion transducer generates digital representations of the reflected images. The motion transducer generates a first set of movement data based on the digital representations of the reflected images. The first set of movement data is indicative of motion of the tip of the digit across the imaging surface.

Abstract: An optical mouse is operated on a work surface and includes at least one light emitter for emitting a light beam; a light receiver contained by a casing; a rolling ball arranged on the casing and opposite to the light receiver. The light beam has only one reflection by the rolling ball during an optical path thereof and then is detected by the light receiver. The rolling ball is made of transparent material and the distance thereof with the light receiver is adjustable to vary image resolution. The optical mouse can be turned over and placed on a notebook computer for using as a track ball.

Abstract: A portable notebook computer includes a base having an exterior surface. A keyboard is mounted on the exterior surface. A palmrest area is mounted on the exterior surface adjacent the keyboard. A scroll device is mounted in the exterior surface adjacent the palmrest area. The scroll device includes a first portion protruding from the exterior surface, and a second portion extending through the exterior surface and recessed into the base. The scroll device is bi-directionally rotatable relative to the exterior surface and resiliently depressible into the base.

Abstract: An input device functions as both a pointing device and a scanning device. The input device can have a switch with a first position in which the input device functions as a pointing device and a second position in which the input device functions as a scanning device. When operating as a scanning device, the input device can have two modes of scanning operation: a document scan mode and a virtual scan mode. In the document scan mode, the input device can scan an image on a document page. In the virtual scan mode, the input device can scan an image on an electronic page. The input device can include a multi-functional scanning system that can scan an image horizontally, vertically, or any angle diagonally relative to a document or electronic page.

Abstract: An image sensor mouse of a contact-less type is provided which employs a full color light emitting diode 80 having a red (R) light emitting unit diode 801, a green (G) light emitting unit diode 802, and a blue (B) light emitting unit diode 803, and a voltage control integrated circuit 910 which makes selection of one or more of the three unit diodes to be operative by varying a driving voltage applicable across each of the unit diodes separately to vary intensity of the emitted light therefrom, whereby obtaining a mixed light in arbitrary color.

Abstract: Disclosed is an optical mouse comprising an image sensor, consisted of a plurality of pixels, for outputting signals accumulated in a given time as a pixel unit, an A/D converter, an image data calculating a moving value of the optical mouse, a system controller for controlling a data flow with an external system, an average value calculator calculating an average value, and a pick-up state discriminator for generating a pick-up state signal. In addition, the optical mouse further comprises a fluorescent lamp state discriminator for discriminating whether the optical mouse is in a fluorescent lamp state and generating a fluorescent lamp state signal.

Abstract: Methods and systems for implementing an improved mouse optical sampling scheme are disclosed. At least one counter state machine is used to control at least one PTR state machine. At least one PTR state machine is used at a sample rate in order to determine the appropriate output for the mouse. The sample rate is adjusted to minimize the system sensitivity to poor duty cycle regulation. In addition, Tmin value(s) are adjusted in order to optimize the duty cycle for each PTR state machine. The mouse output is then provided to the computer. Consequently, by optimizing the duty cycle for each PTR state machine and minimizing its sensitivity to poor duty cycle regulation, a greater dynamic range of optical components can be employed in the mouse.

Abstract: The pointing device of the present invention has a case fixed to a mounting substrate. A sliding-type operating body and moving bodies for moving linearly in X-Y directions in the case as the operating body is slid are provided. Respective side portions of the moving bodies project sideways from the case and lower faces of respective projecting portions face a surface of the mounting substrate. By bringing contacts mounted to the lower faces of the respective projecting portions into contact with a resistor circuit formed on the surface of the mounting substrate, volume portions are formed at two orthogonal side portions. The two orthogonal side portions overhang sideways like eaves and springs for origin returning and are disposed between respective overhanging portions and the respective projecting portions.

Abstract: A device is provided for capturing complete analog motion, rather than digital events. A beam of columnated light, generated from a laser emitting diode, it directed at a clear, rotatable ball bearing having a series of reflecting indicia within the surface of the ball bearing. The reflection of columnated light off of these indicia makes the analog motion of the ball bearing a capturable, optical event. A sensor reads through the clear ball bearing and converts this motion into memory. The raw data then goes into the temporary RAM, which holds all excess data as other date is streamed into the microprocessors. Those processors change the raw data into digital code, which can then be understood and translated by most modern personal computers. The digital code can then be stored in the unit's non-volatile RAM, where it remains until it is uploaded into a PC resident software program.

Abstract: An encoder includes a housing, a light source coupled to the housing, and a light sensor coupled to the housing and positioned to receive a light beam from the light source. The encoder also includes a wheel having opaque and transmissive sections which may be positioned to pass through the light beam before it reaches the light sensor. The encoder further includes a floating aperture piece, which defines at least one aperture. The aperture is positioned so that the light beam must pass through it before reaching the light sensor. The floating aperture piece slidably engages the housing while allowing a loose tolerance between a position of the wheel and a position of the housing, thereby substantially eliminating a positioning error between the aperture and the wheel.

Abstract: A pointing device integrates an IR transceiver into the pointing device. An infrared communication link may then be established between another device and the IR transceiver on the pointing device. The pointing device then relays communication between the host computer and the other device along its cable to the host computer. A user interface involves placing the cursor of a graphical user interface over an icon or other area of the screen. Communications initiated by the user are then sent to that area of the screen, or an action indicated by the icon is taken.

Abstract: A gel cushion that can be attached to an existing cursor pointing device (control stick) on a computer or keyboard, or be integrally formed with the cap during manufacture. The gel cushion is flexible enough to prevent tissue damage to the user's fingers due to repetitive motions over an extended period of use, yet firm enough to transmit the desired pressure to the control stick. The gel cushion designed to be used on an existing control stick can be applied with an adhesive to a cap, or with a frictional fit directly to the control stick. The gel cushion is designed to be easily installed and replaced when worn.

Abstract: A mouse structure includes a base and a cover mounted to the base. A recess is defined in a front portion of the cover for receiving buttons therein. A first far infra-red emitting member is connected to an underside of the cover and each of the buttons has a second far infra-red emitting member received therein.

Abstract: A computer mouse which has a number of features protecting it from damage when dropped. Additionally, the mouse of the invention is designed with features that make it more easily graspable and less likely to drop out of a user's hand in the first place. Finally, aesthetic features are built in to the design of the drop-resistant features. In one aspect, the present invention provides buttons on the top, front of the mouse which are recessed and shielded by a frame to avoid damage when dropped. In addition, the buttons are set back from the nose or front of the mouse so there would not be direct forces on the buttons if dropped on its nose. In another aspect, the invention provides a horizontal slot in an encoder shaft support assembly. Thus, the shaft is blocked from popping upward in a conventional slot arrangement when dropped.

Abstract: A device for operating a mouse-operated computer program includes a base having an upwardly projecting handle firmly secured thereto. The handle may also be linked to the base for fixing in any desired position relative to the base. The handle includes an operating means on top of the handle and/or one of the sides of the handle, and/or on the actual base in order to provide signals which can control the position of the mouse pointer on a computer screen. Rolling balls or similar sliding means are provided on the underside of the base.

Abstract: A hand-writing input and recording device is housed in a case and may be hand-held by a user when in use. The device includes a contact element, an amplifying element, a sense element, an X-Y axes matrix element, a recording and storing element, a transmitting element and a receiving element. When the contact element generates a displacement variation in the X-Y axes, the X-Y axes displacement variation value will be emitted from the transmitting element to the receiving element and input into a computer for display on a computer screen to show the characters or patterns generated from the X-Y axes displacement variation value.

Abstract: A third-axis input device of a mouse comprises a hollow roller stage mounted on a base of the mouse and a hollow roller pivotally arranged on the mouse's roller stage. The roller projects from the cover of the mouse. The roller has a closed lateral surface and an open lateral surface, defining an accommodation space therein. A ring is formed on an inner side of the closed lateral surface and extends within the accommodation space. The ring has a plurality of equally spaced apart tooth-shaped strips formed on a surface thereof to function as an encoder wheel. The encoder wheel is mounted with respect to an optical means having a case, a circuit board connected to the primary circuit board of the mouse, and an infrared transceiver.

Abstract: A sensor for sensing movement of an encoder. At least two sensors are mounted adjacent the encoder. Each of the sensors provides an output corresponding to the amount of movement. A pair of comparators are connected to the sensors to provide two signal outputs. The comparator outputs are then provided to a digital encoding circuit which encodes the signals as a multi-bit serial value on a single output line. The bit value can be read by forcing control pulses onto the output line through an input buffer connected to the same line. The use of the single output line eliminates the extra output pin of the prior art, enabling a three pin package to be used.

Abstract: In an operating device having an actuator (1) with at least two adjustment degrees of freedom, provision is made for said device to have a device (3, 5, 6) for evaluating the position of the actuator (1) optically.

Abstract: A methodology is provided for build-up of a variety of aesthetically pleasing highly ordered patterns which may, by known print processes, be applied to cover the entire spherical surface of a ball used in a computer input device, to thereby render the ball optically trackable with known optical tracking engines. While highly regular in order and appearance, the patterns resulting from the inventive methodology have an inherent or natural geometric variability permitting the patterns to be tracked without aliasing effects and associated cursor jump or skip encountered with previous attempts to optically track a regular arrangement of pattern elements.

Abstract: A roller retainer for the third axis of a mouse comprises a seat, an upper cover and a roller seat. The seat has a housing, a circuit board and other components. The circuit board is installed with a microswitch and an IR module seat. A via hole is formed at the middle portion of the roller seat. The via hole serves to place a roller seat therein. A rear end of the roller seat is buckled to the rear inner end of the upper cover, and the roller seat may be like a suspending arm. The roller seat has a function of plastic resilient and therefore, no elastic spring is necessary. The roller seat is installed with an upper cover and other components is still installed in the seat. Therefore, no space in the circuit board is occupied and thus cost is reduced and material can be prepared easily.

Abstract: A reading pen for reading text has an elongate casing with a reading opening (3) formed in one end thereof, a printed circuit board (5) which is arranged inside the casing, light-emitting diodes (7a, 7b)) arranged inside the reading opening and adapted to illuminate the text that is to be read, and a light-sensitive sensor (9) arranged inside the reading opening and adapted to read the illuminated text. The printed circuit board (5) has an end portion at said one end of the casing. The end portion essentially corresponds to the form of the casing. The light-emitting diodes (7a, 7b) and the light-sensitive sensor (9) are arranged on said end portion.

Abstract: The present invention provides a multiple-wheel input device comprising a positioning plate, two light-penetrating type encode wheels, a circuit board, and two hollow rollers. The light-penetrating type encode wheel is connected pivotally to both sides of the positioning plate. A gap hole is disposed at the central part of the bottom edge of the positioning plate. Two inclined surfaces are formed at the top edge of the gap hole. An arched board is installed at each side of the gap hole. A fixing bar is installed adjoining to each side of the bottom edge of the gap hole to join the circuit board. A light-emitting device is installed at the central part of the circuit board. A light-receiving device is installed at each side of the light-emitting device. The hollow roller is connected pivotally to the circumference of one side of each encode wheel and outside the two arched boards. When the roller is turned, the encode wheel is jointly turned synchronously.

Abstract: A cursor control method, and an apparatus and a memory medium which stores a program related thereto controls a position of a cursor displayed on a screen based on an input from a pointing device. The cursor control method includes the steps of detecting a present position of the cursor based on the input from the pointing device, and (b) controlling a moving quantity of the cursor on the screen based on the input from the pointing device depending on mask information which indicates a specific region on the screen and the present position of the cursor.

Abstract: A method and apparatus for replacing two separate photo detectors chips and two photo emitters by a single photo detector chip and a single photo emitter. This is achieved by using CombiDisks having a flexible shaft. The flexible section allows for the bending of the CombiDisks so that the encoder disks are next to each other and tangent to the same vertical plane. This allows for the placement of both the x and the y sensors in a single plane. This will in turn allow for the two photo detectors to be integrated in a single semiconductor chip, saving a separate photo detector chip, and its associated packaging. This additional savings is significant since the packaging itself contributes to approximately one half of the cost of such a detector.

Abstract: A method and apparatus for eliminating at least one light emitter and one light detector in a mouse design. This is done by using two conical shaped encoder wheels positioned so that they are almost touching each other. A single light emitter then is used to shine light at the junction, so that it strikes both cones. Adjacently located is a single chip, with two photodetectors integrated on each side. The chip is positioned so that light directed at the first conical encoder impinges on the first group of photodetectors, while light directed at second conical encoder impinges on the second group of photodetectors. Thus, the two photodetectors can be integrated on a single chip, saving a separate photodetector chip. In addition, only a single LED is required.

Abstract: An encoder having a movable element with a first polarized filter coupled to the movable element. A second polarized filter is either stationary, or moves differently from the first polarized filter. A photo-emitter and photodetector are arranged on opposite sides of the two polarized filters. Thus, when the polarized filters are aligned in phase, a maximum amount of light will penetrate to the photodetector. However, as they become out of phase due to movement of one of the filters, the amount of light will decrease, as a function of the amount of movement.

Abstract: A pointing device, such as a mouse, track ball or joystick, having a roller. The roller itself has either a plurality of slits or reflective strips for optical detection. A photoemitter and photodetector are positioned to detect rotation of the roller. Thus, the present invention eliminates the need for coupling to a separate optical encoder. The roller can be depressed to cause the actuation of a microswitch. In a preferred embodiment, the photoemitter and photodetector are aligned along a vertical axis, such that the position information is not affected by the vertical depressing of the roller.

Abstract: A snap-on lens carrier for optical pointing devices has retaining legs which structurally affix the lens to the IC to automatically align and register the lens with the aperture plate of the optical sensor. The lens carrier has a body portion which includes the lens and retaining legs arranged on the ends of the body portion. The retaining legs may take various forms, but in general are perpendicular to the body portion with a retaining detent formed at each of their free ends. The retaining legs are configured so that their length between a bearing area on the body portion and the detent corresponds to the thickness of an optical sensor IC. The retaining legs of the lens carrier are resiliently biased to enable the carrier to snap-on to the IC, and thus attached, the IC and lens function as an integral unit when assembled with the remaining components of the pointing device.

Abstract: Changes in the detent position of a detented control wheel used for the Z-axis in a pointing device are determined in a manner that avoids problems previously experienced. A detented wheel is coupled to an optical encoder that produces a quadrature output signal. A quadrature state table containing entries defining quadrature state change conditions that invoke position change indications is used to determine when transitions between detent positions are reported and includes provision for reporting transitions between detent positions even if quadrature states are missed. Also employed is a physical-to-logical quadrature state conversion scheme that enables the transition point between adjacent detent positions to be correctly determined within a controlled range relative to the adjacent detent positions, regardless of the physical quadrature state while the wheel is in a detent position.

Abstract: The present invention discloses a mouse scroll input apparatus for controlling scrolling motions in a computer window, including a signal input device for generating an input signal in response to an operation of a mouse user, wherein a scrolling speed of the window is determined by a level of the input signal. According to the present invention, convenient operation can be achieved at low cost.

Abstract: A detented encoder, employed for sensing a rotation of a wheel by a user between detent position, and suited for use in a pointing device or other user input device. The detented encoder includes a light emitter, a pair of photodetectors, and a codewheel. Interruption of light emitted by the light emitter and received by the photodetectors is processed by a logic circuit to produce a quadrature signal indicative of the detent position of the wheel. The codewheel is integral to a shaft that is supported at one end by a support bracket connected to the lower case of the device. The wheel rotates the shaft when turned by a user. The shaft includes a plurality of evenly-spaced, longitudinally extending spline teeth. A biasing member or opto spacer is operatively coupled to the lower case and includes a base portion on which the light emitter and photodetector are mounted. The biasing member includes a cantilever portion.

Abstract: An encoder wheel module and circuit board arrangement for an optical mouse with scrolling function, which includes a circuit board having a microswitch, a mount mounted on the circuit board, the mount having an integrally-formed bottom frame, an integrally-formed suspension arm spaced above the bottom frame, and an integrally-formed connecting portion connected between the bottom frame and the suspension arm at a rear side, the suspension arm having a front tongue suspending above the microswitch, an optical encoder wheel supported on the suspension arm, a transmitter mounted on the mount at one side and controlled by the circuit board to emit a light beam through radial slots at the optical encoder wheel, and an optical detector mounted on the mount at one side opposite to the transmitter and controlled by the circuit board to read the light beam transmitted by the transmitter, wherein the optical encoder wheel not only provides scrolling up and scrolling down functions when rotating the encoder wheel, but a

Abstract: The invention relates to a pointing device using two linear sensors and fingerprints to generate displacement signals. The pointing device comprises a housing, a linear image input device having first and second linear sensors parallel to each other and installed inside the housing for sensing a linear image and generating corresponding first and second linear image signals, and an image processing circuit installed inside the housing and connected to the two linear sensors for receiving and processing the first and second linear image signals generated by the two linear sensors.

Abstract: The input device of the present invention includes: a base having a slide surface; a movable body slidable on the slide surface; a light-emitting element for emitting light; a reflective portion which is provided for the movable body and has a reflective surface for reflecting the light emitted by the light-emitting element; and a plurality of light-receiving elements for receiving the light reflected by the reflective portion.

Abstract: The present invention relates to an improved structure of a shield used in a computer mouse. The shield includes a generating part and a receiving part which are formed by integration and arranged linearly for constructing the reflecting shield for the mouse. To make the manual work for inserting the shield into the circuit board of the mouse can be done by just one action of composition to avoid the time of actions of repeatedly inserting electrical elements into the circuit board and to reduce the production cost.

Abstract: A pointing device including a ball engaging one or more shaft encoders, each shaft encoder having an encoding wheel, including a monolithic photosensitive array for detecting light pulses representative of rotary movement of the ball. The photosensitive array provides a plurality of resolutions and permits accurate tracking of rotary movement of the ball without need for a mask. Comparator and latch means operate on the output of the array and provides digital hysteresis.