Abstract: A key-board type input mechanism suitable for inputting large quantity of data is provided to a portable information technology device having a pen-input type display device. A keyboard (33 or 35) of the present invention comprises a key top panel portion (12 or 17) on which a plurality of input key portions (12a or 18) that are pressed down when carrying out a key input are integrally formed, a coordinate position information generating portion (13) and contact portions (16 or 19) for changing loads generated by pressing each input key portion of the key top panel portion down into a vertical load, a load distribution portion (14 or 20) for distributing unnecessary loads other than the vertical load changed by the coordinate position information generating portion and the contact portions, by deformation under a pressure. The key top panel portion, coordinate position information generating portion, contact portion, and load distribution portion are layered.

Abstract: An apparatus and method for preventing poor operation of a key due to chattering noise are provided. The apparatus includes a control button section for generating a key signal to control a display monitor, and a microcomputer which contains a control program for preventing poor operation of a key due to chattering noise in the key signal generated by the control button section. The microcomputer detects the key signal when the chattering noise is generated, determines whether the key signal is in a normal state or not, and processes the key signal. When the chattering noise is generated in a tactile switch of the control button section of the display monitor, the AD port of the microcomputer detects it, and determines whether or not the key operates normally, thereby preventing poor operation of the key due to the chattering noise.

Abstract: A Caps Lock notification method, system, mechanism, algorithm, and computer program product. A determination is made as to whether a Caps Lock key of a computer keyboard is in an error state, based on ascertaining whether a first condition has been satisfied. If it is so determined that the Caps Lock key is in an error state, then a signal is generated to communicate to a user at the computer keyboard that the Caps Lock key is in the error state. The signal may be a visual signal, an audible signal, a tactile signal, an auditory signal, or a combination thereof. Satisfaction of a second condition may be used to disable the signal.

Abstract: A computing device includes a keyboard controller that is adapted to convey an operator input from the keyboard controller along a communications channel. Also included is a battery module, which is interfaced to the communications channel, for receiving the operator input. The computing device further includes a memory element located within the battery module for recording the operator input.

Abstract: A method for testing a keyboard complied with a language code table comprises the steps of reading an embedded language code of the keyboard to be tested through a central processing unit (CPU), comparing the read language code with the language code table stored in memory in order to determine whether there is a matched one, reading an application program interface (API) function from the keyboard to be tested by the CPU, identifying a type of the keyboard to be tested by a “Get Keyboard Type” of the API function, reading exchange codes of special keys from the keyboard to be tested by the CPU, identifying a model of the keyboard to be tested, selecting a keyboard test software corresponding to the language code, the type, and the model of the keyboard to be tested from a test software database stored in memory, and performing a test on each key on the keyboard by the selected keyboard test software.

Abstract: A keyboard with a numbers of keys disposed on the base is capable of showing the three-dimensional characters. Each key includes a shell and a three-dimensional character embedded in the shell. Combined with an illuminant module positioned between the base and keys for providing the light source, the three-dimensional characters can be shown clearly and distinguishably by utilizing the color contrast relation with light between the light-colored transparent three-dimensional characters and dark-colored or opaque shells.

Abstract: A touch screen capable of isolating noise signals is mainly a touch screen installing at the front side of a liquid crystal display (LCD) screen or cathode ray tube (CRT) for eliminating electromagnetic and radio frequency interference received by the LCD and CRT. The touch screen includes an antenna like conductive wire which is able to receive same noise signals mixed in the touch control signals. The touch screen controller uses the noise signals received by the antenna wire to offset the noise signals in the controller for increasing accuracy of the touch screen.

Abstract: A wireless keyboard may be provided with a guard protocol which prevents unintended typematics. An alive signal may be periodically generated to advise a host processor-based system that the keyboard communication link is still effective. If the host processor-based system receives a key make signal but does not receive a break signal or an alive signal, the processor-based system may deduce that the link has gone inactive, and may generate its own break signal. This avoids unnecessary power consumption and unnecessary typematics.

Abstract: A dual-function keyboard with two operational modes, a typing mode and a pointing mode. In the typing mode, each visible key functions as in a standard keyboard. In the pointing mode, all the keys function as pointer controllers. The keyboard also employs a novel “one-hot-encoding” circuitry that simplifies the wiring while allowing digital detection of any number of keys that are simultaneously depressed. The keyboard may be made of flexible materials and may be rolled-up or folded for easy transportation.

Abstract: An improved multi-function key assembly (12) is provided. The multi-function key assembly includes a printed circuit board substrate (28) having a popple dome switch array (26) mounted thereto. Attached to the substrate is a button member (22) adapted for use as a data input device for an electronic device. The button member has a central area or region (48) and a contoured peripheral surface (30) serving as a plurality of perimeter key regions (32-46). The contour of the peripheral surface provides a user with tactile feedback in determining the location of the various key regions. The button member additionally includes a plurality of plungers (54-68, 72) extending from its bottom surface (70). Each plunger corresponds to a specific key region and is capable of actuating a popple dome switch (154, 156) for that specific key region. The assembly may include a base (76) having a plurality of legs (90).

Abstract: A keyboard is placed into a suspend mode. Upon the detection of the pressing of a key, the keyboard processor is wakened from the suspend mode. No power is consumed during the suspend mode, sine the keyboard processor is not scanning the key matrix. The key matrix drive circuitry may also be tested by monitoring a signal emanating from the key matrix drive circuitry and scanning each of the drive lines in the key matrix. If the signal is altered, then the associated drive line in the keyboard drive circuitry is defective. Testing of sense circuitry is performed by changing pull-up resistors to pull-down resistors and then reading sense lines.

Abstract: An apparatus and a method for increasing the number of keys in a ready made key-matrix , it is necessary to increase some extra diodes and change the keyboard scanning method . To increase some extra keys in the key-matrix, the diodes are in series with the keys, and the keyboard scanning method is executed by detecting the conductive direction of the diodes. The method avoids redesigning any IC to increase I/O ports, therefore, it can save the cost of redesigning and advance the sale.

Abstract: A digital cordless telecommunications unit that serves for communications when paired with a similar unit and connected with a network is disclosed. The unit receives and transmits analog voice signals and also transmits digital baseband signals and receives digital formatted baseband signals. The unit includes a baseband chip, as well as an audio functions block and a system control functions block. The audio functions block comprises an audio front end for receiving and transmitting the analog voice signals and an adaptive differential pulse code modulator codec, connected to the audio front end. The codec converts the analog voice signals to the digital baseband signals and converts the digital formatted baseband signals to the analog voice signals for transmission.

Abstract: A combination keyboard and pointing device is incorporated in a portable computer and includes a dielectric base member on a top side of which a spaced series of electrically conductive pad member portions of a capacitance-based proximity sensing system are formed. Manually depressible key members are positioned above the pads. With the sensing system switched to a typing mode, the pads capacitively sense the proximity, velocity and acceleration of a user's fingers depressing their associated keys and output signals useable by the computer to display the character associated with the depressed key. A sensed increased stroke velocity of each manually depressed key may be used to alter the key character image displayed on the screen, for example capitalizing, bolding or underlining the character.

Abstract: A touch operation information output apparatus is provided in a position at which a driver can operate it, and detects a touched position with respect to the input pad and outputs its coordinate data to the display device. Here, protruding brackets are provided at 16 positions on the input pad. A first group of protruding brackets that are in 4 positions at a center of the input pad are formed in a “+” shape, a second group of protruding brackets that are in four corners of the input pad are formed in an “L” shape and a third group of protruding brackets are formed in a “T” shape. Because of this, the driver can recognize the touched position with respect to the touch operation information output apparatus and blind operation becomes possible.

Abstract: A method for entering a special mode of an electric device in which the special mode such as a test mode exists. According to the method, at least two coded keys are continuously inputted. From an initial key input, the coded keys are inputted in respectively predetermined amounts of time to enter the special mode. The special mode is not entered when: (1) only one of the coded keys is inputted; (2) the continuously inputted keys are not inputted in the respectively predetermined times; or (3) a combination of the continuously inputted keys is not the same with a combination of predetermined keys.

Abstract: A method for transmitting key characters representative of keys on a keyboard is provided. A probability of use for one or more of the key characters may be determined by counting the number of occurrences of the key characters for a predetermined time period or for a literary work. Alternatively, the number of occurrences of one or more of the key characters may be calculated in real time and the probability of use adjusted accordingly for the key characters. Based on their calculated probability of use, the key characters are mapped into transmission formats. A system and a keyboard are also disclosed which map key characters into transmission formats based on probability of use of the key characters. Additional methods are disclosed for using error detection data in the transmission formats. Exemplary error detection may include adding parity bits or configuring the data in the transmission formats to indicate errors.

Abstract: A computer in which entry of data from an area provided on a display, touch screen or the like is accomplished by the provision of a "soft keyboard". Misentry of data is avoided by providing for the adjustment of the input by raising the area of input by a fixed percentage of the size of the target soft key.

Abstract: A key handling circuit for a switching matrix having row and column conductors includes bidirectional drives for the row conductors and the column conductors. The row drive and the column drive are in a low conductive condition except when a relevant key switch is activated. The row drive provides a current input for the column drive in one phase of operation and the column drive provides a current input for a row drive in a second phase of operation.

Abstract: A selective calling receiver includes a keypad for inputting an instruction according to a user's manual operation and a detector for detecting an incoming call addressed to the selective calling receiver itself. A notifying circuit notifies reception of the incoming call to a user through sound, light, and/or vibration. When the incoming call is detected, a control processor transfers control to an incoming call notifying routine and, at the same time, ignores the instruction received from the keypad during a predetermined time period immediately after the incoming call has been detected. After the predetermined time period has passed, the instruction due to the user's manual operation is enabled again.

Abstract: A method and apparatus for losslessly compressing binary data using a technique referred to as Double Run-Length Encoding (DRLE). DRLE has particular application to the compression of gray-scale data as it is being processed for printing by a laser printer or other continuous raster scan device. DRLE records repeating patterns of ones and zeros with little computational complexity. Compression ratios that may be an order of magnitude or more are obtained frequently on data that may not compress well using traditional Run-Length Encoding (RLE). DRLE uses a sequential history of order-pairs that denote variable-length patterns of zeros and ones, and then encodes these patterns as they repeat themselves.

Abstract: In an electronic musical instrument which generates musical tone signals based on playing information input from a key switch circuit 10, a key scan circuit 11 includes a decode circuit 22 to which the current status information and the previous status information read out from a scan data memory 21 are input, and if status information which cannot be processed is input, the decode circuit 22 converts it to status information which can be processed, and if there is no empty space in an output data buffer 24, the decode circuit 22 detects no status change. Such construction allows malfunction to be prevented with a simple construction.

Abstract: A method and apparatus for identifying authorized users of a secure system. A user of the secure system is prompted to enter a personal identification code which is then received into the secure system. The personal identification code entered by the user is then compared against a list of authorized personal identification codes. The user is identified to be an authorized user of the secure system only if the personal identification code entered by the user is present in the list of authorized personal identification codes. Each personal identification code on the list of authorized personal identification codes is arranged in a personal identification code format that includes a plurality of core digits and a plurality of check digits.

Abstract: The present invention is directed to a system and methodology where virtually no DC power dissipation is used during keyboard scanning or key closure. This is done by replacing the passive pull-up (or pull down) resistors of previous schemes by input/output (I/O) circuits with repeaters and utilizing a scanning protocol and methodology which take advantage of the bidirectional I/O devices with repeaters. In a preferred embodiment, a plurality of CMOS bidirectional I/O circuits with repeaters are used, one for each row and column line in a switch matrix. A low power, switch activation scanner circuit determines activation of a switch. The circuit is coupled to or may include a plurality of switches, arranged in rows and columns, each row output line intersecting each column output line at a different node, for coupling a first row to a first column at a first node when a first switch of the plurality of switches is activated.

Abstract: In one embodiment, the method and related apparatus for configuring and operating a computer keyboard includes providing a personal computer system having a monitor, central processing unit, memory, sound generator and a keyboard input/output interface. The keyboard is substantially flat and has a planar user interface surface with a plurality of discrete membrane switches protruding a small distance (less than one-eighth of an inch) above the surface. In addition, each switch is circumscribed by a key channel. The domes of each membrane switch enhance the tactile response to the child or young adult learning to use the keyboard because upon depression of the key face, the dome deforms into a concave shape and closes a normally open circuit junction in a key switch matrix beneath the user interface surface. The method as well as the apparatus electrically blocks the generation of multiple digital key strike signals whether based upon continual actuation of one of the key switches (i.e.

Abstract: A fault tolerant method of decoding an electronic key system includes the steps of reading a key return image from one or more actuated keys and comparing the read key return image to the previous key return image. The method also includes the steps of determining the actuated key from a net key return image between the read key return image and the previous key return image.

Abstract: A n-key rollover keyboard having an application specific integrated circuit (ASIC) with a large number of pins, each pin directly connected to a key contact, with the other side of the key contact connected to ground. The direct wire arrangement allows use of a single sided circuit board. The keyboard has a reduced cost over prior n-key rollover designs by allowing removal of the series diodes and double sided circuit board.

Abstract: A key signal input circuit for a microcomputer including a microprocessor and a single input port. The microcomputer outputs, in sequence at a constant interval, a plurality of grid signals, receives different key signal inputs successively through the single input port synchronously with the grid signals, and discriminates the inputted key signals to recognize which keys have been selected. The key signal input circuit includes a power supply circuit, responsive to the grid signals from the microcomputer, having a plurality of power supply lines for supplying, in sequence at a constant interval, a desired power through the power supply lines. A key matrix circuit having a plurality of sets of keys, responsive to the desired power through the power supply lines from the power supply circuit and to on/off states of the keys, coupled, by sets, respectively to the power supply lines. The key matrix circuit applies the key signals successively to the microcomputer.

Abstract: A keypad scanner mechanism which may be incorporated with an integrated circuit including a microcontroller. The keypad scanner mechanism includes a keypad with more than one key. The keypad scanner mechanism has an activity detect mode and a normal mode. In the activity detect mode, the keypad scanner mechanism wakes up the integrated circuit and triggers the normal mode. In the normal mode, the keypad scanner mechanism identifies and reports to the microcontroller the depression of keys on the keypad. The keypad scanner mechanism also includes a means for debouncing, a multiple keys down code, and a no keys down code. The keypad scanner mechanism is suitable for any keypad application, however, it has been found that the keypad scanner mechanism is especially suitable for incorporation into the base and handset units of a cordless telephone that integrates the speech, control channels, and microcontroller portions of a modem, and the man-machine interface functions of a cordless telephone.

Abstract: A data processor (50) includes a hardware keyscan circuit (54) to interface to an external keypad matrix (80). In one embodiment, the data processor (50) has a first register (62) for driving data to rows of the keypad matrix (80), and a second register (63) for inputting signals from columns of the keypad matrix (80). A set of weak pullup elements (71) connected to the columns is always conductive. A set of strong pullup elements (75) connected to the columns is conductive only after the hardware keyscan circuit (54) detects that a key (89) is depressed and disables the driving of the rows. Thus, pullup time and power consumption are minimized. The hardware keyscan circuit (54) also includes a data direction register (61) which has a shift control input terminal so that in response to a local state machine (64), the data direction register (61) acts as a shift register to sense the row with the depressed key (89), without intervention from a central processing unit (51).

Abstract: A method of detecting the status of a keyboard switch device judges validity or invalidity of the status of switching elements on the basis of simple conditions. With this method, processing of output data is facilitated. In a step S1, a scanning operation is carried out to detect the status of each switching element. In a step S2, the result of the scanning operation is stored in a memory unit as memorized information. In a step S3, closed element total number N, a closed row total number Nr, and a closed column total number Nc are counted with reference to the memorized information. In a step S4, a judgement is made as regards whether or not a predetermined condition is satisfied by the closed element total number N, the closed row total number Nr, and the closed column total number Nc. When the predetermined condition is satisfied, the memorized information is provided as valid data in a step S5.

Abstract: Disclosed is a scanning circuit for an electrical matrix keyboard. The keyboard has extended keys on a voltage line and a ground line. Two extended line detector are incorporated into the circuit for detecting the extended keys without increasing input and output ports of the circuit, so that the circuit can be integrated into a chip at a lower cost.

Abstract: The REAL TIME KEYBOARD SCANNER shown herein provides scanning and debouncing, but not multiple key resolution or buffering. At the end of each keyboard scan, the scanner produces a code indicating which key was depressed, or that no key was depressed, or that multiple keys were depressed. If this code is the same as the code in a valid-key register, then no change is made to the valid-key register and no debouncing is performed. If the codes differ, then debouncing is performed. The CPU served by the scanner can examine the code in the valid-key register whenever it finds such examination to be convenient, and need not tie up valuable processing time in continuously monitoring the valid-key register. If desired, an interrupt may be sent to the CPU when the code in the valid-key register is changed.

Abstract: A data processing apparatus receives key codes corresponding to keys depressed on a plurality of keyboards. These key codes are sequentially stored in a first-in first-out (FIFO) buffer awaiting processing by a central processing unit (CPU). If successive key code entries correspond to an auto repeat key (e.g., a space key, a backspace key, an underline key, a move cursor key, etc.), a determination is made whether the auto repeat key codes are the same. If they are, the CPU processes the subsequent auto repeat key code. If they are different, the CPU ignores that auto repeat key input. In another embodiment of the present invention, one of the keyboards is hardwired to the data processing system while a second keyboard is connected via a wireless link. Auto repeat key codes are only accepted from the first wire-connected keyboard, and any auto repeat key codes from the second wireless keyboard are ignored.

Abstract: A circuit for recognizing double key inputs includes a key input part, a key signal generating part, a comparing circuit and a detecting part, the key signal generating part operates simultaneously with the key input of the key input part and generates a key signal which is provided to the comparing circuit which outputs a high level only at the time of two or more key inputs. A high level output of the comparing circuit is added to an output voltage of the key input part when two or more keys are pressed. The circuit provides the advantage that double key inputs can be easily recognized with a minimum number of key input lines.

Abstract: Debounce and lockout filters include an input part for receiving a plurality of input signals from switches, a microprocessor and an output part. The filters simultaneously process a plurality of input binary signals in parallel according to a sequence of mask values which individually adjust the filter response function for each of the individual filter channels. A multichannel filter has a filter simultaneously filtering each input signal of a plurality of input signals, the filter including a plurality of independent filter channels, each independent filter channel filtering a corresponding input signal of the plurality of input signals to produce a corresponding output signal of a plurality of output signals. The multichannel filter also has a mechanism for independently adjusting a filter response time of each independent filter channel.

Abstract: A keypad monitor implemented in an integrated circuit monitors the closure of a plurality of keypad switches coupled to input terminals of the integrated circuit. The keypad monitor is operative in a first mode for monitoring a first number of the input terminals and a second mode for monitoring a lesser number of input terminals. When in the second mode, the unmonitored input terminals are converted for a use not related to keypad monitoring.

Abstract: A key scan circuit and the method thereof in a microcomputer is disclosed which requires no diode for preventing circuit short and performs key check or automatic operations with a simplified circuit structure. The key scan method includes a step of designating the input/output mode of a bilateral port by a data direction register in a microcomputer which includes an input/output bilateral port and an input only unilateral port, so as to prevent circuit shorts when more than one key are pushed. Further, by using first and second memories, the key scan method includes a step of determining whether the number of logic low states in the first memory is greater than one, and determining whether the number of logic high states stored in the second memory is greater than one, thus indicating the pressing of multiple keys.

Abstract: A keypad status reporting system provides an indication over a serial bus as to which switch of a plurality of keypad switches is being selected by an operator wherein each keypad switch is coupled between a respective different pair of row and column conductors. The system generates parallel three-bit row and column addresses, combines the row and column addresses to form a parallel six-bit key code, and converts the key code to serial bits of data and places the serial bits of data onto a multiplexed bus in a predetermined channel.

Abstract: A keyboard apparatus includes a key matrix having key switches disposed at intersections between rows and columns forming a matrix and a control unit for selecting a row and a column of the key matrix to sense a state of a key switch disposed at an intersection of the selected row and the selected column of the key matrix. The apparatus includes a first confirmation unit for sensing, in a first period of time, a key switch state of the key matrix to confirm whether or not two or more depressed keys exist on a row of the key matrix and a second confirmation unit for sensing again, in a second period of time, a key switch state of the key matrix such that when two or more depressed keys exist on a column of the key matrix, a confirmation is made to determine whether or not two or more depressed keys exist on the row on which the key depression is found in the key matrix.

Abstract: An electronic device has an operating section having a plurality of input keys. The operating section is detachably connected to a body of the device in such a manner that the contacts of the operating section are electrically connected to the contacts of the body when the operating section is connected to the body. The body includes a connection detecting section for detecting the connection of the operating section to the body to output a connection detection signal; and a control section for making the connection of the contacts of the body and the contacts of the operating section effective a predetermined period of time after provision of the connection detection signal.

Abstract: A touch responsive user selection system including a plurality of touch pads on an insulated substrate and a logic circuit for responding to the change of impedance of any of the pads for setting or resetting a latch and thereby producing an output signal indicative of a user selection. A coincidence detector responds to the simultaneous change of impedance of two or more different touch pads by inhibiting the logic circuit from producing an output signal both during the coincidence and for a predetermined period of time after the coincidence has ceased. The logic circuit is made up of components that are arranged in a fashion that causes the circuit to respond to a ratio of signals that vary in proportion to supply voltage. In this manner, a touch-responsive system is provided that may be used with an unregulated power supply while functioning with extreme variations in supply voltage.

Abstract: The present invention is a fault detecting membrane potentiometer keyswitch. The keyswitch includes circuitry for providing a reference voltage signal when not activated, so that a faulty switch can be determined by absence of a reference voltage signal. Specifically, the wiper of the membrane potentiometer keyswitch is coupled to the resistive element of the keyswitch intermediate a sensing portion and a reference portion. With this arrangement, as long as the keyswitch is inoperative, the reference portion provides a reference voltage signal which is distinguishable from any of the setting voltage signals, and also distinguishable from a grounded condition. When a setting signal is observed, a timer is used to determined whether the setting signal is a user entered setting signal or a short between the wiper and the resistive element.

Abstract: A heating cooking appliance includes a heater for the cooking, a switch generating an operation signal while being touched or depressed with a finger or the like, and a microcomputer for controlling the heater so that energization of the heater is initiated in the case where the operation signal generated by the switch is continuously input into the microcomputer for a predetermined period of time. The heater is not energized only when the switch is touched by accident or mistake. When a user depresses the switch for the predetermined period of time with the intention of initiating the cooking, the heater is energized.

Abstract: The present invention is directed to a circuit arrangement for adjustment of the triggering point of the keys in an inductive keyboard. The keyboard consists essentially of a printed circuit board designed in a matrix-like manner, comprising coils superimposed upon each other, into which a ferrite pin plunges when a key is actuated. By the cooperation of a pulse generator with a current switch which can be influenced through control lines, said cooperation being controllable by a microcomputer, a current pulse is coupled from one coil to another coil and is recognized as a readout signal by a controllable readout amplifier and is conducted further to a central unit. The adjustment of the triggering point of the keys is accomplished by varying the steepness of the driving current pulse, for example, by means of a blocking time duration in the charging of a capacitor determined only once, which durations are stored in a table of values, or it is derived from the fundamental interlinked signals of the keys.

Abstract: A method of determining a phantom key condition in an encoder array (10) including (1) enabling each row (R1-R14) of the encoder to a high position; (2) pulling the first row (R1) to be scanned to a low position; (3) scanning the first row (R1) of which in the low position finding whether there is a first key being closed, (4) determining whether there is second key being closed in the first column (C2) of which the first key has been closed, if there isn't a second key being closed, then outputting the signal, if there is a second key being closed, then (5) determining whether there is a third key being closed in the second row of which a second key has been closed before, if there isn't a third key that exists, output the signal, if a third key exists in the second row, (6) then the phenomenon of a phantom exists and the inputting signals will be invalid and beeper sound is emitted to warn the typist.

Abstract: A solid state touch or control button assembly (10), with no moving button parts and operated by capacitive sensing by monitoring the phase shift of a signal applied to the face of the button, including in a first embodiment (FIGS. 2A & 2B) a auto balancing button and in a second embodiment (FIGS. 3A & 3B) a constant pressure button. If skin or other material comes into contact with the touch surface, the capacitance is changed and sensed, causing the electrical or electronic function controlled by the touch button to be activated (or deactivated, depending on the design, or otherwise altered). LEDs then are activated, providing visual feedback to the button pusher through a light ring (2A) surrounding the button surface (1).

Abstract: In a keyboard operation two sequential keystrokes are used for generation of a character code. A rule is set up according to which some preset combinations of two sequential keystrokes are valid and others are not. The rule is implemented by storing the validity conditions into a table in a control unit. According to a preferred rule the second key to be operated must be located in a column to the right of the column where the first key is located, otherwise an error signal will be generated. The method is preferably used for a one hand keyboard with three times four keys.

Abstract: An input key apparatus comprises a keyboard including a plurality of keys and generating key signals when keys are pressed and a key input decoder receiving the key signals from the keyboard for generating decoded key signals. The key input decoder also generates a single key depression signal when a key of the keyboard is pressed one time, and a multi-key depression signal when two or more keys of the keyboard are simultaneously pressed. A chattering prevention circuit receives the single key depression signal and the multi-key depression signal for determining on the basis of the received signals whether or not the key signal received by the decoder is valid, for the purpose of generating a key input valid signal. An output circuit receives the decoded key signals for latching the decoded key signal in response to the key input valid signal.

Abstract: A frequency number corresponding to the frequency of a tone intended to be sounded is accumulated in an accumulator at every calculation timing of a constant interval to produce values progressing at a rate corresponding to the tone frequency. At this rate, waveform amplitude value samples are sequentially produced one after another in a tone producing section using the output of the accumulator as phase angle data. A reset circuit is provided in connection with the accumulator and this circuit functions to compulsorily reset the progressing values in the accumulator to its initial value in response to a carry out signal generated at the calculation timing when the phase angle data has reached its predetermined modulo value. Thus the period of progress of the phase angle data is harmonized with the calculation timing, i.e., the sampling timing.