A display matrix of LEDs responds to two coordinate display input signals representative of display positions each defined by a respective LED in the matrix, an input switch unit adapted for use by a disabled person being coupled to the matrix, so that the user can selectively actuate any one of a plurality of the LEDs, by a microprocessor equipped with an ROM holding the operating program for the microprocessor and an RAM in which sets of position coordinates of the matrix can be temporarily stored and recalled under the control of the user so that the user can write a message into the RAM by selecting a sequence of matrix positions corresponding to a sequence of words visibly displayed at respective LEDs and subsequently recall and display the message by selecting a read position in the matrix.
An improved technique for driving matrix displays, and in particular, passive matrix displays including row and column configurations of electro-optical display elements (e.g., liquid crystal, LED, plasma, and Electroluminescent). By analyzing illumination information about display elements, a matrix display is more effectively driven. Also, by using the method, the selection ratio in LCD displays is improved.
A number of LEDs 6 are vertically and horizontally arrayed on a printed circuit board 5, thereby forming a display surface. Switches 7 for turning on or off the LEDs 6 and keeping them in an on or off state are provided at locations corresponding to or close to the LEDs 6. With this construction, the LEDs 6 can be turned on or off directly from the display surface.
A modular messaging sign panel contains a plurality of LEDs coupled to a plurality of latched drivers. A microcontroller on the panel has a unique serial number permitting the panel to be selectively addressed by a host. The microcontroller receives serial data representing an image frame, selects the data intended for the panel in which it controls and clocks it out to the latched drivers along a single serial data line. Multiple panels can be connected to form a larger display panel system. Each panel has its own uniquely addressed microcontroller. A three wire connection couples the panel or display system to a computer and a power supply. A single jumper wire connects each modular panel together such that the data output from the computer is received by every microcontroller within the system in a parallel configuration. Accordingly, each microcontroller is receiving all the data outputted from the computer but only selects certain data for distribution to the latched drivers coupled to the LEDs on its particular panel based upon an ID match. Power and ground are supplied to a multi-panel system via power and ground rails of a frame structure upon which the panels are mounted.
According to the present invention, a heating pad controller incorporating a discrete ASIC (Application Specific Integrated Circuit) is provided which varies the duty cycle characteristics of a periodic signal during which power is applied to a heating pad heating element during a portion of the signal ("on" time). An oscillator circuit is used to produce a controlled duty cycle control signal for controlling the power applied to the heating pad by varying the on-time of the duty cycle. User control of the length of the on-time of the duty cycle is provided by way of a user controlled switch, thereby providing for a plurality of controller operating modes (e.g., WARM, LOW, MEDIUM, HIGH, etc.). To configure the duty cycle for each heat setting the heating pad controller utilizes switchable electrical components of varying impedance connected to the ASIC. A heating pad controller according to the present invention can be configured for use with heating pads of varying sizes simply by installing electrical components with the appropriate impedance during manufacture of the circuit board.
