Patent Publication Number: US-6210010-B1

Title: Illuminated pushbutton with colors and brightness electronically controlled

Description:
FIELD OF THE INVENTION 
     The invention relates to an illuminated pushbutton with variable color lights which are electronically controlled and wherein the light is emitted utilizing solid state devices. 
     More particularly the invention deals with a momentary action or alternate action switch realized without electromechanical commutation. (“Momentary action” means the generation of an electrical or electronic signal for the entire time the button is maintained active. “Alternate action” means the generation of an electrical or electronic signal which changes in state each time the pushbutton is pushed.) The pushbutton of the invention has an illuminated part consisting of a display which can be divided in independent zones, illuminated with visible light generated inside the button having a wavelength programmable independently for each zone. The zones can be of any number. The pushbutton described in the following is the version divided in four zones. 
     The invention is in the field of the electronic devices and is applicable to command/control illuminated pushbuttons for mechanical, electrical and electronic equipment. It can be used in the naval, avionic, space fields, and the pushbutton can support any stress even when the device s in operation. 
     The invention represents an advance in control pushbuttons. The display light is obtained by solid state components. The pushbutton configuration is such that the zones can be colored with any desired color, and these colors can be electrically changed depending on the user needs. 
     BACKGROUND OF THE INVENTION 
     The pushbuttons on the market to the best of our knowledge, are constituted by a switch and a display. The switch generally is mechanical and has a limited life because of the use of mechanical contacts and springs. Mechanical and electrical switching jumps are unwanted negative effects. Such effects generate false signals to be eliminated by electronic means. 
     Until now in such pushbutton, the part activated by the operator is illuminated by lamps which generate a base light similar to white light and to obtain different colors, filters and optical corrections are employed. These lamps do not permit changes in the emitted light color. 
     Operating rules and the human engineering prescriptions require the use of lighting of different colors and brightness. For instance, white light is used to permit the reading of information and the identification of the command by the operator; red light is used to read out alarm states and variable lighting (green, blue, amber, etc) can be used depending on the operative conditions. 
     Lamps have a limited useful life and require access into the illuminated pushbutton for the replacement of failed lamps. 
     To verify the presence of failed lamps it is necessary to implement a lamp test function that the operator activates using a specific command. The off state of the lamps, creates ambiguity between the condition of failed lamps or a deactivated state of a lamp. 
     SUMMARY OF THE INVENTION 
     The drawbacks described above are overcome by the illuminated pushbutton of the invention. 
     The pushbutton has a display made of solid sate components able to supply light, for instance LEDs, in the colors, red, green and blue. By mixing them any light color in the visible light spectrum can be generated without using filters. (Even the intensity can be electronically controlled). 
     The color switching and intensity are obtained electronically. 
     The pushbutton allows the activation of electric/electronic switching devices, for example conductive rubber switches, solid state switches, etc. 
     The pushbutton can be used to carry out millions of operations without incurring disadvantages caused by wear. 
     The MTBF values (Medium Time Between Failure) attainable are such to eliminate any need for maintenance work. 
     This illuminated pushbutton can also be employed in cockpits and in command and control panels in mechanical and electric and electronic equipment. 
     The display illumination is obtained by solid state components, through which it is possible to produce light of any color, even white. The display has unlimited working life by comparison with previous displays. 
     “Lamp tests” are not necessary. 
     The display is cold to the touch, even in maximum luminosity conditions. 
     The display is subdivided in zones and each zone can be illuminated independently both as to luminosity and to color. 
     The color of each zone can be dynamically varied in accordance with operational conditions. The possibility of change the color of the light, in a dynamic way, satisfied any rules prescribed. It is therefore possible to illuminate any zone with white light to facilitate the reading of legends and of the background, making it readable also in ambient sunlight. 
     A special switch actuator is employed which is able to control switches without mechanical contacts for instance, conductive rubber or solid state optical switches allowing unlimited numbers of operations even in severe shock and vibration conditions. 
     The pushbutton can be used in many configurations just by modifying the internal electronic circuits. For instance, by properly modifying the electronic circuitry alternate functions (bistable) of the electric contacts or direct control can be obtained through external commands of emitted light. The illuminated pushbutton can be used with many kinds of serial communications using several standard hardware and software protocols. The pushbutton can also include an internal microcontroller. 
     Another advantage of this invention is that the illuminated pushbuttons can be applied on panels, individually or in a matrix pattern. The matrix version offers compactness and reduction of the space, weight and cost and a better quality for a smaller number of parts utilized. 
     The input-output pushbutton connections are realized by direct coupling through motherboards or crimp connectors. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
     FIG. 1 is a side view of a pushbutton according to the invention; 
     FIG. 2 is top view of the pushbutton; 
     FIG. 3 is a section as seen from the side; 
     FIG. 4 is an exploded view of the display; 
     FIG. 5 is an exploded view of the pushbutton; 
     FIG. 5A is a perspective view thereof; 
     FIGS. 6A-6H are views showing various configurations of the display; 
     FIG. 7 is a perspective view of a pushbutton housing for matrix assembly; and 
     FIGS. 8 and 8A show the pushbutton assembly matrix configuration in an elevational and cross sectional view. 
    
    
     SPECIFIC DESCRIPTION 
     With reference to FIG. 1, the display assembly  5 , constituted by a movable part  3  and a fixed part  4 , includes the flange  2  for mounting in a panel  36  and is joined to the switch assembly  6  to constitute the pushbutton. The clamping spacer  8 , clamped by the cam  9 , is opposite to the flange  2  for clamping the pushbutton on the panel  36  by compression of the mounting gasket or seal  11 . The pushbutton is closed on the rear side by a cover  7 . Also the input-output connector  10  is on this side. 
     In FIG. 2, the illuminated area  1 , the flange  2  and the movable part  3  of the display can be seen. 
     As can be seen from FIG. 3, the pushbutton comprises a display assembly of which an exploded view is seen in FIG. 4 having a display cover  12  which is mechanically connected to the display housing  13  by a mechanical latch  27 . The display housing  13  encloses optical devices  18  are enclosed. These optical devices include transparent elements  40 , a label  41 , an optical diffuser  42  as may be necessary to obtain any optical performance required. The reflector  14  is utilized to direct the light emission of the solid state elements  15 . The housing display  13  includes slide guide  28  which allows the movable element  3  of the display to shift along the actuator axis. The pushbutton gasket  20  (FIGS. 3 and 5) is employed to seal the pushbutton internal parts to avoid humidity or other contaminating elements in the switch zone  6  (FIGS.  1  and  5 A). The mounting gasket  11  (which is not visible in FIG. 4) is mounted under the flange  2  to form a seal against external agents like water. The flexible circuit elements  16  is clamped by the screw  43  and sealed in the regions  17  and  21  to make the electrical connections between the display assembly ( 5 ) and the other parts of the pushbutton. The sealing out of the external agents at the front is obtained by the display gasket  19 . The transmission of the movement in the pushbutton is effected by the actuator support  44 . 
     The switch assembly  6  comprises the switch shell  51  (FIG.  5 ), the rear input-output cover  7 , the spring guide  32 , the actuator pin  31 , the switch actuator  25 , the spring  33  and the rubber switch  24 . The movement along the vertical axis, effected by moving of the movable part  3  of the display, moves the switch actuator  25  and then presses the spring  33  housed in the spring guide  32  to activating the rubber switch  24  to give the switching function. 
     The vertical axis movement of the actuator is guided by the actuator slide guide  29 . The actuator slide guide  29  and a washer  50  are of plastic to protect the metallic parts against damage by wear and abrasion. 
     The pushbutton electrical connections are realized by the flexible circuit  23  (FIG. 5) an the electronic components  30 . 
     The connector  22  connects the display assembly with the switch. The electronic parts are housed in the zones  26  (FIG.  3 ). The electric connections of the pushbutton to the exterior are obtained by connector  10  mounted on the flexible circuit element  23 . 
     FIGS. 6A-6H show some of the many configurations in which the display can be realized. 
     FIG. 7 represents a matrix housing  45  for assembly of single pushbutton  46  in a matrix pattern. 
     The example shows a four-row three column matrix. It can thus contain twelve single pushbuttons. Each pushbutton inserts in the direction of the arrow  47  and when assembled, it reaches the position represented by the pushbutton  46 . Even the flange  48  of this matrix has a gasket  49  to avoid contamination by external agents. 
     FIGS. 8 and 8A show a pushbutton matrix assembled during the manufacturing. It is a version with four rows and two columns, that is with eight illuminated pushbuttons. 
     In this case the fixed parts of the display  4 , represented in FIG. 3, are substituted by a flange  54  on which the parts which constitute the pushbutton are assembled. 
     The pushbutton activation is effected by applying a proper pressure on the illuminated area  1 . This action causes the shifting of the movable part  3  and then the movement on the axis of the switch actuator  25 , the pressure on the switch  24  until the activation and then the generation of the signal electrical command. The travel of the display movable part is limited by a mechanical block between spring guide  32  and the actuator slide  29 , while the spring  33  restores the initial position of the pushbutton when the pressure on the illuminated area  1  stops. The lighting is activated by electronic command applied through the connector  10 , the flexible  24 , electronic parts  30 , connector  22 , flexible circuit  16  to the solid state elements  15  which are LEDs or similar components.