Switch apparatus requiring the hand of the operator to activate the switch by breaking a light beam

Abstract

A manually operable switch apparatus for a machine having at least one mode of operation actuated by a control circuit includes a spaced pair of switches which are simultaneously manually operable without the application of exertive contact by an operator. Preferably, each switch includes an infrared emitter spaced from an infrared receiver, and a single or double pole, double throw relay actuated when the beam between the emitter and receivers are broken, so as to cause actuation of an alternative mode of machine operation. The use of switches which do not require exertive contact obviates the injury to wrist and finger tendons experienced by machine operators when conventional palm buttons are employed on machines requiring repetitive operator manipulations. The use of a spaced pair of such switches requires that the operator place both hands on the switches in order to operate the machine, so that the operator cannot inadvertently place a hand in or adjacent to the machine during operation, thus serving to prevent injury to the worker. Such a switch apparatus is substantially more reliable then conventional mechanical and pneumatic switches, subject to significantly less breakdown in use.

We claim:  
     
       1. For use in conjunction with a machine having a mode of operation in which the machine is actuated to perform a machining operation and a circuit responsive to two input signals, said circuit preventing operation of said machine in said mode unless said circuit receives said input signals substantially simultaneously, 
       a pair of switch assemblies for producing said input signals, each switch assembly comprising:  
       a housing having a generally U-shaped opening having sides and a bottom, said opening being dimensioned to allow the introduction of a human hand into said opening between said sides and to said bottom,  
       a photo optical switch contained in said housing, said photo optical switch producing an output signal upon the introduction of a human hand into the opening and without contact between the human hand and the photo optical switch and without the necessity of the hand applying an exertive force,  
       means for electrically connecting the output signal from each photo optical switch as an input signal to said circuit to enable operation of said machine in said mode.  
     
     
       2. The invention according to  claim 1 , wherein said photo-optical switches comprise proximity switches. 
     
     
       3. The invention according to  claim 1 , wherein said photo-optical switches each comprise an infrared emitter and an infrared receiver spaced from said emitter. 
     
     
       4. The invention according to  claim 1 , and comprising an anti-tiedown logic circuit to which each of said photo-optical switches are operatively connected. 
     
     
       5. The invention according to  claim 1 , and comprising an actuation circuit having parallel limbs, each of said limbs being associated with disparate operative modes of said apparatus, and wherein said photo-optical switches each comprise an at least single pole, double throw, break-make solenoid actuated relay, operatively connected to said limbs, and means for energizing said relay. 
     
     
       6. For use in conjunction with a machine having a mode of operation and a circuit responsive to two input signals, said circuit preventing said mode of operation unless said circuit receives said input signals substantially simultaneously, 
       
         a pair of switch assemblies for producing said input signals, each switch assembly comprising:  
       
         a housing having a generally U - shaped opening defined by a pair of substantially vertical side members with opposed facing surfaces extending upwardly from a bottom surface, said opening being of sufficient size to allow the introduction of at least a portion of a human hand thereinto;    
         a photo - optical switch contained in said housing, said switch including a light emitter supported immediately adjacent one of said side surfaces and a light detector supported immediately adjacent the other of said side surfaces, such that the light from said emitter travels directly to said detector along a straight path defining a beam,    
         said photo - optical switch producing an output signal upon the interruption of said beam through the introduction of a human hand into the opening of said housing without contact between said hand and the bottom of said housing, and without the necessity of said hand applying an exertive force; and    
         means for electrically connecting the output signal from said photo - optical switch as an input signal to said circuit to enable operation of said machine in said operational mode.   
     
     
       7. The invention according to  claim 6 , wherein said beam is substantially horizontal. 
     
     
       8. The invention according to  claim 6 , wherein said beam is infrared. 
     
     
       9. The invention according to  claim 6 , further including an anti- tiedown logic circuit operatively connected to each of said photo - optical switches.   
     
     
       10. The invention according to  claim 6 , further including: 
       
         an actuation circuit having parallel limbs, each of said limbs being associated with a disparate operational mode of said machine; and  
       
         a double - throw relay operatively interconnecting said photo - optical switches to said limbs.   
     
     
       11. The invention according to  claim 6 , wherein said switch assemblies are sufficiently spaced apart so as to obviate simultaneous operation by a single hand of an operator. 
     
     
       12. For use in conjunction with a machine having first and second disparate modes of operation and a circuit responsive to two input signals, said circuit preventing one of said modes of operation unless said circuit receives said input signals substantially simultaneously; 
         a pair of switch assemblies for producing said input signals, each switch assembly comprising a housing having a generally U - shaped opening defined by a pair of substantially vertical side members with opposed facing surfaces extending upwardly from a bottom surface, said opening being of sufficient size to allow the introduction of a portion of a human hand thereinto, and a photo - optical switch contained in said housing, said switch including a light emitter and a light detector supported on either side of said opening so as to establish a light beam thereacross;    
         said photo - optical switch producing an output signal upon the interruption of said beam without contact between said hand portion and the bottom of said housing, and without the necessity of said hand portion applying an exertive force;    
       
         an actuation circuit having parallel limbs, each of said limbs being associated with one of said disparate operational modes of said machine; and  
       
         a double - throw relay operatively interconnecting said photo - optical switches to said limbs to enable operation of said machine in only one of said operational modes at any given time.   
     
     
       13. The invention according to  claim 12 , wherein said beam is substantially horizontal. 
     
     
       14. The invention according to  claim 12 , wherein said beam is infrared. 
     
     
       15. The invention according to  claim 12 , further including anti-tiedown circuitry characterized in that one throw of said relay is operatively connected to said anti- tiedown circuitry for each mode of machine operation.   
     
     
       16. For use in conjunction with a machine having a mode of operation and a circuit responsive to two input signals, said circuit preventing said mode of operation unless said circuit receives said input signals substantially simultaneously when an operator exerts force onto a pair of manually operable switches, a method of updating the control of said machine, comprising the steps of: 
       
         removing said manually operable switches while leaving said circuit intact;  
       
         providing a pair of housings, each having a generally U - shaped opening defined by a pair of substantially vertical side members with opposed facing surfaces extending upwardly from a bottom surface, each opening being of sufficient size to allow the introduction of at least a portion of a human hand thereinto, and an optical switch assembly disposed in each opening for producing said input signals; and    
       
         connecting said optical switch assemblies to said circuit.